Baseline characteristics of all infants born at <27 weeks’ GA who reached 2 years’ CA in 2018–2020, and separately for infants born at 24 weeks’, 25 weeks’ and 26 weeks’ gestation
| Total | 24 weeks | 25 weeks | 26 weeks | P value | |
| Live born (N) | 991 | 271 | 297 | 423 | |
| Died before admission (N (% of live born)) | 100 (10.1) | 59 (21.8) | 24 (8.1) | 17 (4.0) | |
| Admitted (N (% of live born)) | 891 (89.9) | 212 (78.2) | 273 (91.9) | 406 (96.0) | |
| Died after admission (N (% of admitted)) | 240 (26.9) | 98 (46.2) | 68 (24.9) | 74 (18.2) | |
| Survived to 2 years’ CA (N (% of admitted)) | 651 (73.1) | 114 (53.7) | 205 (75.1) | 332 (81.8) | |
| Follow-up data available (N (% of survived)) | 554 (85.1) | 98 (86.0) | 178 (86.8) | 278 (83.7) | |
| Maternal age | 30.3 (5.2) | 30.7 (5.1) | 30.6 (5.2) | 30.1 (5.3) | 0.437 |
| Birth weight (g) | 820 (150) | 697 (99) | 799 (120) | 876 (154) | <0.001* |
| Sex (male) | 288 (52.0) | 46 (46.9) | 93 (52.2) | 149 (53.6) | 0.524 |
| SGA (<tenth percentile) | 99 (17.9) | 5 (5.1) | 27 (15.2) | 67 (24.1) | <0.001* |
| Caesarean section | 185 (33.4) | 14 (14.3) | 50 (28.1) | 121 (43.5) | <0.001* |
| Multiple birth | 154 (27.8) | 23 (23.5) | 51 (28.7) | 80 (28.8) | 0.573 |
| 5 min Apgar | 7(6, 8) | 7(5, 8) | 7(6, 8) | 7(6, 8) | <0.001* |
| Severe NEC | 63 (11.4) | 10 (10.2) | 21 (11.8) | 32 (11.5) | 0.919 |
| Severe brain injury | 85 (15.3) | 15 (15.3) | 27 (15.2) | 43 (15.5) | 0.996 |
| SES | 0.251 | ||||
| Low | 141 (25.5) | 25 (25.5) | 46 (25.7) | 70 (25.3) | |
| Intermediate | 338 (61.1) | 53 (54.1) | 111 (62.4) | 174 (62.8) | |
| High | 74 (13.4) | 20 (20.4) | 21 (11.8) | 33 (11.9) | |
| Maternal education | 0.100 | ||||
| Low | 63 (11.4) | 18 (18.4) | 14 (7.9) | 31 (11.2) | |
| Intermediate | 195 (35.2) | 37 (37.8) | 58 (32.6) | 100 (36.0) | |
| High | 208 (37.5) | 30 (30.6) | 78 (43.8) | 100 (36.0) | |
| Missing | 88 (15.9) | 13 (13.3) | 28 (15.7) | 47 (16.9) |
Birth weight is presented as mean (SD), Apgar score is presented as median (Q1,Q3), other variables are presented as N (%). SGA is defined as birth weight below the tenth percentile. A value of p<0.05 is considered statistically significant. *, significant at 0.05 level
CA, corrected age; GA, gestational age; NEC, necrotising enterocolitis ; SES, socioeconomic status; SGA, small for gestational age.